Lohmann wore an aluminized suit close to the lava lake at the heart of the Benbow crater for protection from the heat.

Smoke and gas steam from a volcanic crater.

The team anchored their ropes at the rim of the Benbow crater and slowly abseiled down in three sections.

The climbers look down into the Benbow crater.

Most people's idea of a good night's sleep involves a plush mattress, blackout shades, and maybe some sleeping pills. But Ulla Lohmann catches her best zzz's hundreds of feet deep inside a rumbling volcano, lava casting a red glow all around. "It's like a night light," she says.

The German photographer loves volcanoes so much her husband proposed to her atop one, and then the couple honeymooned on another. She's spent the last decade exploring 10 active volcanoes around the world. But Lohmann's favorite part is abseiling, or rappelling by rope hundreds of feet into the churning, lava-filled core.

“This is the most intriguing thing, being so close to the heart of the Earth,” she says. “It’s the feeling of being really close to creation.”

Lohmann's obsession started on a family trip to Pompeii when she was eight. After high school, she serendipitously met a National Geographic crew while on a trip in the South Pacific, and convinced them to let her tag along as a camp assistant during a three-week expedition to photograph the nearly 1,000-foot deep Benbow crater on the volcanic Ambrym island, Vanuatu. Lohmann distinctly remembers standing at the edge of an active crater for the first time. "I thought, ‘Oh my gosh, this is cool. But I want to go further,’” she says.

She spent the next few years studying volcanoes, rock climbing, and saving up money for gear. Lohmann has explored many volcanoes over the years, but it wasn't until 2014, when she traveled back to the Benbow crater with her assistant Sebastian Hofmann and vulcanologist Thomas Boyer, that she was finally able to rappel inside one. It didn't go well. They were on their down to the fiery core when it began to rain; the water, gushing through volcanic gas, turned to acid, threatening to dissolve their ropes and pulling loose a torrent of sharp rocks. “We had a discussion about who would die first,” she says. “Nobody wanted to be left alone.”

The team abandoned its mission but returned again the next year, with much more success. The group spent three nights in the upper reaches of the crater, dozing on a wide ledge with nothing but sleeping bags and gas masks to protect them from toxic fumes. "You have to be careful that you don’t shift too much in the night," Lohmann says. Then, the final part of the journey, a 38-hour down-and-back: as they got closer to the core, the team donned shiny aluminized heat suits and thick gloves to protect their hands. They finally reached the bottom, where a lava lake as wide as a football field simmered and bubbled—its temperatures around 2,200 degrees Fahrenheit. “The earth is trembling constantly, like you’re walking on jelly, and it's rumbling and roaring and really really loud,” she says. “You have two inches of crater wall above you and just a bit of skylight at the top—and you realize that you're at the center of the Earth.”

Her photos depict that wonder, pulsing with the bright blinding heat of the lava and tiny figures dwarfed in the glow. It's a peek into a world few people will ever see—unless, of course, you're the sort of person who likes to have a sleepover inside a volcano.

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